Create helper functions to use in computeInvariantOutput calls

src/gpu/effects/GrDashingEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDashingEffect.h"
 
 #include "../GrAARectRenderer.h"
@@ skipping 567 matching lines @@
     if (info.fCount != 2 || info.fIntervals[0] != 0) {
         return NULL;
     }
 
     return SkNEW_ARGS(DashingCircleEffect, (edgeType, info, radius));
 }
 
 DashingCircleEffect::~DashingCircleEffect() {}
 
 void DashingCircleEffect::onComputeInvariantOutput(InvariantOutput* inout) const {
-    inout->fValidFlags = 0;
-    inout->fIsSingleComponent = false;
+    inout->mulByUnknownAlpha();
 }
 
 const GrBackendGeometryProcessorFactory& DashingCircleEffect::getFactory() const {
     return GrTBackendGeometryProcessorFactory<DashingCircleEffect>::getInstance();
 }
 
 DashingCircleEffect::DashingCircleEffect(GrPrimitiveEdgeType edgeType, const DashInfo& info,
                                          SkScalar radius)
     : fEdgeType(edgeType)
     , fInCoord(this->addVertexAttrib(GrShaderVar("inCoord",
@@ skipping 202 matching lines @@
     if (info.fCount != 2) {
         return NULL;
     }
 
     return SkNEW_ARGS(DashingLineEffect, (edgeType, info, strokeWidth));
 }
 
 DashingLineEffect::~DashingLineEffect() {}
 
 void DashingLineEffect::onComputeInvariantOutput(InvariantOutput* inout) const {
-    inout->fValidFlags = 0;
-    inout->fIsSingleComponent = false;
+    inout->mulByUnknownAlpha();
 }
 
 const GrBackendGeometryProcessorFactory& DashingLineEffect::getFactory() const {
     return GrTBackendGeometryProcessorFactory<DashingLineEffect>::getInstance();
 }
 
 DashingLineEffect::DashingLineEffect(GrPrimitiveEdgeType edgeType, const DashInfo& info,
                                      SkScalar strokeWidth)
     : fEdgeType(edgeType)
     , fInCoord(this->addVertexAttrib(GrShaderVar("inCoord",
@@ skipping 43 matching lines @@
     switch (cap) {
         case GrDashingEffect::kRound_DashCap:
             return DashingCircleEffect::Create(edgeType, info, SkScalarHalf(strokeWidth));
         case GrDashingEffect::kNonRound_DashCap:
             return DashingLineEffect::Create(edgeType, info, strokeWidth);
         default:
             SkFAIL("Unexpected dashed cap.");
     }
     return NULL;
 }